Preparation and use of tabs or marking labels containing yarns of partially saponified cellulose acetate



United States Patent 2,998,631 PREPARATION AND USE OF TABS 0R MARKINGLABELS CONTAINING YARNS 0F PARTIALLY SAPONIFIED CELLULOSE ACETATE PeterMeyer, London, and Victor Emmanuel Yarsley and Witold Titow,Chessington, England, assignors to Polymark Limited No Drawing. FiledNov. 20, 1956, Ser. No. 623,313 Claims priority, application GreatBritain Nov. 22, 1955 15 Claims. (Cl. 28--73) The present inventionrelates to improvements relating to the marking of articles and isparticularly concerned with the temporary marking of textile articles bymeans of a tab or label which consists in part of thermoplastic materialand which is caused to adhere to an article to be marked under theaction of heat and pressure in the presence of a solvent, the procedurebeing such that the marking tab or label can be s'ebsequently peeled orremoved from the article. Such marking of articles is required forexample for identification purposes in the case of garments to besubjected to laundry or dry-cleaning operations and also for pricemarking of articles where it is desired that the marking tab or labelshall be readily removable.

For temporary marking of articles it will be realised that in somecircumstances difiiculties may be encountered in fulfilling all thevarious requirements which may be met. It is obvious that in the case ofany removable tab or label the label must be capable of beingsubstantially completely removed from the marked article without leavingany residue of material on the article, but nevertheless a comparativelyfirm bonding must be obtained to prevent accidental removal of the tabor label. This problem arises particularly in the case of tabs or labelsfor laundry or dry-cleaning marking and in this case the labels mustalso withstand hot detergents or solvents in some cases, while themarked articles are subjected to various handling or treatingoperations. Furthermore, in many cases such labels are required to carryprinted identification markings which must remain clearly legible aslong as the tab or label remains adherent to the article, but there mustbe no transfer of the printing material from which the characters areformed on the marked article.

Various proposals have heretofore been made for the use of marking tabsor labels formed in part from thermoplastic material and such methodsare mostly based on the use of cellulose acetate as the thermoplasticmaterial. By the term cellulose acetate used herein there is to beunderstood commercial cellulose acetate consisting mainly of secondarycellulose acetate predominantly or completely soluble in ketonesolvents, such as acetone or methyl ethyl ketone. The labels aregenerally cut from a fabric tape including cellulose acetate yarns, suchlabels being applied to an article to be marked under the action of heatand pressure in the prmence of a solvent. The cellulose acetate may bein the form of staple fibre or in mono-filament or multiple-filamentform; the invention may also be applied to blended yarns consisting inpart of cellulose acetate.

To facilitate the removal of the tab or label it has been proposed toleave an edge portion of the tab or label unadhered to the article forexample by applying the heat and pressure over less than the wholesurface of the tab or label or an edge portion may be made non-adherentto the article in other ways.

With proper control in manufacture and in the means employed forapplying the tabs or labels under heat and pressure to an article in thepresence of a solvent, satisfactory and reliable results can be secured,but under unfavourable circumstances and on unfavourable textilearticles, small but undesirable amounts of residue of cellulose acetatehave been left on the marked article after removal of the tab or labeltherefrom, and the present invention is particularly directed to theproblem of reducing such residue to the smallest possible amount so thatthe marked articles can for all practical purposes and under all normaloperating conditions be regarded as substantially free from residue.

In accordance with the present invention this result is obtained bysubjecting a cellulose acetate substance comprised by a marking tab orlabel or intended to be incorporated therein, to a partialsaponification treatment such that at least part of the depth of thesubstance is afiected by such treatment, such treatment being controlledand regulated in such manner that adhesion to an article under heat andpressure in the presence of a solvent is not adversely affected to anyappreciable extent while the amount of residue left on the article afterthe tab or label has been removed is reduced in comparison with anuntreated substance.

Experience has shown that by suitable treatment of the cellulose acetateit is possible to reduce the amount of residue to a very small andsubstantially negligible value. In some cases this reduction in theamount of residue may be coupled with an improved adhesion compared withthe untreated cellulose acetate while in other cases the adhesion may besubstantially unaffected or may lie at a value which is satisfactory inpractical operation. The treatment of the cellulose acetate required ishowever of a somewhat critical character since if the treatment iscontinued for an unduly long period the adhesion may be seriouslyreduced. It is difficult to specify the effects of the treatment of thecellulose acetate by physical criteria other than by specifying that thetreatment must be such that the final result shows a noticeablereduction in the residue as compared with the untreated celluloseacetate and that the adhesion is either increased or is at least notreduced to an extent which adversely affects the usefulness of thelabel.

The cellulose acetate may be treated according to the invention atvarious stages in the production of the finished label. In the case of afabric label including cellulose acetate yarns, the yarns may be treatedbefore weaving the label fabric therefrom or the woven fabric or tapecut therefrom may be treated.

Whatever procedure is adopted the acetyl number of the cellulose acetateis not affected to a substantial extent and the result of the treatmentis believed to be that part of the depth of each fibre or filament ofthe cellulose acetate yarn is subjected to partial saponification to adepth of perhaps one-third of the radius, but the present invention isnot based on any particular theory as to the reasons why improvedresults are obtained as a result of the treatment.

Various saponifying agents can be used but in general it can be statedthat hydroxides, and in particular alkali metal and alkaline with metalhydroxides, such as sodium hydroxide or barium hydroxide, or metal saltsof a basic nature such as sodium carbonate or soda ash can be used. Itis preferred however to use strong organic bases such astriethanolamine.

Various methods of carrying the invention into effect may be adopted,for example, a woven or knitted fabric intended for the formation oftabs or labels and formed in part from cellulose acetate yarns, may betreated by being immersed or passed through a bath containing asaponifying agent which may also include a swelling agent. The fabric ispreferably woven or knitted in such manner that the cellulose acetate isexposed to a greater proportionate extent on the face which is adheredto the article to be marked than on the other face, which may carry anidentification mark.

Any of the saponifying agents indicated above can be adopted and in somecases such agents also serve as their own swelling agents. The treatmentcan be performed at room temperature or at an elevated temperature andin general the time of treatment varies inversely with the temperature.Since the treatment may tend to be rather critical and if the time oftreatment is exceeded there 15 the danger that adhesion is lost, it ispreferred that a comparatively long treatment time is adopted to enablesatisfactory control of the treatment to be effected. In general controlis effected by determinlng the time of treatment so as to securesatisfactory final results and once said time has been determined forgiven treatment conditions a simple routine check from time to time 18suflicient to ensure consistent results.

In the case of cold treatment the preferred treatment baths includetriethanolamine as the saponifytng agent and cyclohexylamine as theswelling agent, the ratio of the swelling agent to the saponifying agentbeing an important factor in determining the treatment time. Baths ofthis character may require a treatment time of the order of 48 hours aswill be explained in greater detail in the following examples.

If on the other hand treatment is effected at an elevated temperaturesuch as 100 C. triethanolamine can be used without any separate swellingagent and the time of treatment may be of the order of 6 /2 hours.

Attention is directed to the fact that if the treatment is carried onfor too long the result is that a tab or label including the treatedcellulose acetate does not exhibit proper adhesion and it is believedthat the reason for this result is that the outer skin of each celluloseacetate filament has been de-acetylated and therefore is no longerpermeable to the solvent medium commonly applied to the labelimmediately before it is applied to the article to be marked, even underthe action of heat and pressure.

Thus in one example of treatment according to the present inventionapplied to the treatment of a woven fabric including spaced yarns ofcellulose acetate of the character disclosed in British specificationNos. 561,989, 650,- 910 and 735,236, the fabric is passed through a bathcontaining soda ash. The time and temperature of treatment and theconcentration of the treatment bath are so chosen that the resultingfabric when used for laundry marking purposes, for example by themachines described in British specifications Nos. 644,119 and 695,708leaves less residue on a marked article under given operating conditionsthan an untreated tab or label, without adhesion being impaired. In somecases the adhesion is even improved. The invention may also be appliedto fabrics of similar properties produced by knitting techniques such asa Warp-knitted fabric.

In the application of other re-agents the use of triethanolamine hasproved to be very convenient as it has been found that treatment is lesscritical than with inorganic bases and there is the further advantage oflow volatility. It is found that with this material no observablereaction occurs for a certain initial period. This initial period may beof the order of one hour. After this initial period saponificationproceeds relatively slowly to a point at which the adhesive propertieshave reached a maximum value while residue has reached a low value.After this point the adhesive properties are reduced.

It is obvious that the treatment according to the present invention isoperated to give results approximating the optimum but not so closethereto that incidental changes in the working conditions result in theloss of adhesion.

Several examples of methods of carrying the present invention intoeffect are given below and in each case a range of treatment times isgiven. The difference between these times represents what may be termedthe control period over which it is desirable to make tests to ascertainwhen the treatment of the cellulose acetate yarn has been such as toprovide the required results while avoiding the fault of loss ofadhesion. Examples 1 to 3 cover a. cold treatment at room temperaturewhile Examples 4 to 6 comprise hot treatment.

In the following examples, fabrics woven (or knitted) from cotton yarnsand cellulose acetate yarns as described in one of the aforesaidspecifications are treated in the particular baths described, afterwhich the fabric is slit to form the desired lengths of marking tape.

Example 1 The fabric is treated for a period between 2 and 5 minutes ina solution consisting of 0.1 N alcoholic potash. In this case thetreated fabric is then dried at 70 C. without washing.

Example 2 The fabric is treated in a solution containing by weight 2.5%triethanolamine and 0.5% cyclohexylamine. The fabric is then rinsed anddried. The time of treatment ranges between 48 and 49 hours.

Example 3 The fabric is treated in a solution containing by weight 5%triethanolamine and 0.5% cyclohexylamine. The fabric is then rinsed anddried. The time of treatment ranges between 49 and 55 hours.

Example 4 The fabric is treated in a solution made up as follows, theparts being given by weight in each case:

40 parts water 3.5 parts sodium sulphate decahydrate 1.7 parts sodiumcarbonate anhydrous 0.3 part of a wetting agent such as Lubrol W 0.25part n-butanol 1 part ethyl alcohol In this case the fabric ispre-treated for 10 minutes with sulphonated Lorol at 60 C. and is thenrinsed and placed wet in the above treatment bath at C. The treatmenttime will range from 10 to 20 minutes.

Example 5 The fabric is treated at 100 C. in a solution of 10% (byweight) triethanolamine. The time of treatment ranges from to 120minutes.

Example 6 The fabric is treated at C. in a solution of 2% (by weight)triethanolamine. The time of treatment ranges from 6 /2 to 7% hours.

In the above examples the triethanolamine used was Gemec water whiteContinental. Further the quality of the water used may have someinfluence on the operation of the process; the above examples were basedon the use of a tap water having pH 7.7 and containing 235 parts permillion total hardness and 65 parts per million permanent hardness.Minor modifications in the treatment time may be required according tothe tension of the fabric; for instance, if the cloth is merely immersedfor a lengthy period in the bath the treatment time required may beslightly different from that applying where the cloth is stretched overrollers and immersed in the bath or where the fabric is passedcontinuously through the bath for example in the case of continuoustreatment. The fabric may also be treated by steeping in the treatmentbath, wrapping or covering with waterproof material, and then leavingthe fabric for the predetermined time.

It will be noted from the foregoing examples that where triethanolamineis used no additional wetting agent need be employed; at lowtemperatures it is preferable to include a separate swelling agent suchas cyclohexylamine, but at an elevated temperature no separate additionof a swelling or softening agent is required.

Correct treatment conditions of time and temperature and other variablesare established by means of tests under conditions reproducing normalworking. When the correct conditions are obtained as shown by anacceptable measure of adhesion and a reduced residue on a marked articleor substantially no residue, the treatment can be proceeded with and theconditions established by test repeated on a quantity basis. Anindependent quick check test may be based on the tensile strength of thecellulose acetate yarn when subjected locally to the action of an agentsuch as glacial acetic acid. For example such a test may be based onsuspending a predetermined length of the yarn and applying a givenweight to the lower end, thereafter applying a single drop of glacialacetic acid to the upper end of the yarn and determining the time beforethe yarn breaks.

After treatment in accordance with the foregoing examples, the fabric issubjected to any other treatments usual in the fabric finishing art andis then ready for the production of marking labels.

The same procedure and the foregoing examples may be applied to tapesproduced from woven or knitted fabrics by slitting and to narrow wovenor knitted ribbons or ribbons produced by lace-making techniques.Substantially similar methods with only minor modifications may beapplied to the treatment of cellulose acetate yarns before weaving intoa fabric.

Tabs or labels produced from label material treated as described abovemay be used for the temporary marking of articles following theapplication of heat and pressure to the tab or label in the presence ofa solvent for cellulose acetate. Such tabs or labels remain firmlyadhered to the article throughout any normal handling operations and canbe withdrawn when required by pulling ofi while leaving little or noresidue on the marked article, the removal being assisted by the factthat one edge of the tab or label is not adhered to the article andserves as a finger grip. This finger grip may be formed either byproviding the tab or label with an edge portion free from acetate yarnsor by applying heat and pressure to a part only of the tab or label.

What we claim is:

1. In a method for producing labels formed partly of cellulose acetateyarn and adapted for temporary attachment by heat and pressure toclothing articles for identification purposes during cleaning which areto be pulled from said clothing articles after cleaning, the improvementcomprising partially saponifying said cellulose acetate yarns beforeattachment to the extent that substantially no residue remains on saidarticle when said label is pulled therefrom and insufficient toadversely affect adhesion to said clothing articles.

2. A method as claimed in claim 1 wherein said cellulose acetate yarnsare saponified by an agent selected from the group consisting of alkalimetal and alkaline earth metal hydroxides, metal salts having a basicreaction, and strong organic bases.

3. A method as claimed in claim 1 wherein said cellulose acetate yarnsare saponified by triethanolamine.

4. A method as claimed in claim 3 wherein said cellulose acetate yarn issaponified prior to formation of said fabric.

5. A method as claimed in claim 3 wherein said cellulose acetate yarn issaponified after formation of said fabric.

6. A method as claimed in claim 3 wherein saponification is efiected ata temperature between room temperature and C.

7. A method as claimed in claim 3 wherein saponific-ation is effected atroom temperature in the presence of a swelling agent.

8. A method as claimed in claim 7 wherein said swelling agent iscyclohexylamine.

9. A method as claimed in claim 3 wherein said label is attached to saidarticle by heat and pressure in the presence of a solvent.

10. A method as claimed in claim 9 wherein said solvent is a ketone.

11. A method as claimed in claim 3 wherein said labels are also formedpartly of non-thermoplastic yarns.

12. A method as claimed in claim 11 wherein said cellulose acetate yarnsare exposed to a greater extent on the fabric surface to be attached tosaid clothing article than on the opposed surface.

13. A label for temporary attachment by heat and pressure to clothingarticles for identification purposes during cleaning which is to bepulled from said clothing articles after cleaning comprisingnon-thermoplastic yarns and partially saponified cellulose acetateyarns, said saponification being to the extent that substantially noresidue remains on said article when said label is pulled therefrom andinsuflicient to adversely affect addesion to said clothing articles.

14. A label as claimed in claim 13 wherein said cellulose acetate yarnsare exposed to a greater extent on the fabric surface to be attached tosaid clothing article than on the opposed surface.

15. A label as claimed in claim 13 wherein said label includes an edgeportion free of cellulose acetate yarns to form a non-attaching fingergrip for pulling.

References Cited in the file of this patent UNITED STATES PATENTS1,884,623 Dreyfus et a1. Oct. 25, 1932 1,897,793 Dreyfus et a1. Feb. 14,1933 1,993,922 Dreyfus et a1. Mar. 12, 1935 2,092,006 Moncriefi Sept. 7,1937 2,193,894 Whitehead Mar. 19, 1940 2,209,238 Sperber July 23, 19402,639,255 Meyer May 19, 1953 2,703,764 Vogt Mar. 8, 1955' 2,765,241Wayne Oct. 2, 1956

1. IN A METHOD FOR PRODUCING LABELS FORMED PARTLY OF CELLULOSE ACETATEYARN AND ADAPTED FOR TEMPORARY ATTACHMENT BY HEAT AND PRESSURE TOCLOTHING ARTICLES FOR IDENTIFICATION PURPOSES DURING CLEANING WHICH ARETO BE PULLED FROM SAID CLOTHING ARTICLES AFTER CLEANING, THE IMPROVEMENTCOMPRISING PARTIALLY SAPONIFYING SAID CELLULOSE ACETATE YARNS BEFOREATTACHMENT TO THE EXTENT THAT SUBSTANTIALLY NO RESIDUE REMAINS ON SAIDARTICLE WHEN SAID LABEL IS PULLED THEREFROM AND INSUFFICIENT TOADVERSELY AFFECT ADHESION TO SAID CLOTHING ARTICLES.